Concept explainers
To determine: The difficulty that a system would pose in which DNA serves directly as the template for polypeptides synthesis.
Introduction: The process that describes the relationship between the DNA, RNA, and proteins is known as the central dogma of modern genetics. It is the basis of genetics because this describes the process of protein synthesis.
To determine: The observations and theoretical considerations that argue against the proposal which consider the possibility that DNA directly serves the template strand for polypeptide synthesis.
Introduction: Proteins are the polypeptides that are made up of different types of amino acids. One amino acid is made up of three
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Concepts of Genetics (12th Edition)
- Question 1: Define and give an example of the following: Codon, Start Codon, Anticodon, and Stop Codon. a) How is information from the DNA code copied and moved to the cytoplasm? b) What are the base pairing rules followed when one DNA strand is read and an mRNA made? Question 2: What eukaryotic sub-cellular structure is responsible for making proteins? a) Is this sub-cellular structure present in prokaryotes? b) What is the name of the enzyme responsible for making the mRNA? c) Is DNA always inside the nucleus of eukaryotic cells?arrow_forwardTransposable elements, “jumping genes”, were first described by Barbara McClintock in her Nobel prize winning studies with corn. The genome of every multicellular eukaryote that has been sequenced is composed of a large percentage of transposable elements (often 30% to 50%), but they are nearly absent from the genomes of eubacteria and archaea. What are these things and what do they do? Describe and draw the structural organization and mechanism for movement of transposons and retro- transposable elements. What effect do these elements have on the stability of genomes? can you help me answer the bolded question?arrow_forwardChristian Anfinsen showed that the enzyme Ribonuclease (RNase) is completely inactivated at high concentrations of beta mercaptoethanol (BME). When BME is removed, it restores only approximately 1% of RNase activity. When a very low concentration of BME is added back to RNase, its activity is restored to nearly 100%. Why? a Low concentrations of BME causes disulfide bonds to break, but they randomly reform. b High concentrations of BME disrupt all disulfide bonds, which inactivates the enzyme. At low concentrations all of the disulfide bonds reform and BME acts as a cofactor for the enzyme. c The enzyme is only active when an intermediate number of disulfide bonds exists. which is achieved only at low concentrations of BME. d The low concentration of BME allows the majority of the proteins to adopt their most stable form, which is the active form.arrow_forward
- An important validation of the genetic code occurred when George Streisinger determined the amino acid sequence of bacteriophage T4 lysozyme and of mutants induced by proflavin, a dye with a planar structure that can intercalate (fit) between successive base pairs in DNA and induce frameshift mutations—that is, mutations involving additions or deletions of a single base. Streisinger and colleagues found that a particular single-base insertion mutation could be suppressed, with wild-type function restored, by a mutation that evidently involved a single-base deletion at a nearby site. Shown below are portions of the amino acid sequence of wild-type T4 lysozyme and the putative double mutant. The remaining parts of the sequence were unchanged. Identify mRNA sequences that could encode each of these amino acid sequences and determine whether your codon assignments are consistent with the genetic code.Wild-type …Lys–Ser–Pro–Ser–Leu–Asn–Ala…Double mutant …Lys–Val–His–His–Leu–Met–Ala…arrow_forwardWhich of the following is a reason why codons are NOT composed of only two nucleotides?Question 22 options: A) It happened by random chance. B) The ribosome is composed of more than 2 subunits. C) The size of tRNAs requires that more than two nucleotides be present in a codon. D) There are 20 amino acids that need to be coded for.arrow_forwardWhich of the following recognizes the mRNA codon 5' - U A A - 3'?Question 29 options: A) a special termination tRNA B) a special termination amino acid C) a special termination protein D) Kozak's sequence E) aminoacyl tRNA synthetasearrow_forward
- What observations are consistent with the conclusion that DNA serves as the genetic material in eukaryotes? List and discuss them.arrow_forwardConsider the following original coding sequence of a gene that codes for a short 5- amino acid polypeptide: 5'-ATGGGCTCGAACTCATAA-3' Using the genetic code and the amino acid table below, which of the following sequences arises from a non-conservative missense mutation in the original sequence shown above? First base in codon U U A UUU UUC- UUA UUG- CUU CUC CUA CUG- U Phe (F) Leu (L) Leu (L) Second base in codon Val (V) UCU - UCC UCA UCG CCU CCC CCA CCG AUU ACU- AUC Ile (1) ACC AUA- ACA AUG Met (M) start ACG GUU GCU- GUC GCC GUA GCA GUG GCG- C Ser (S) Pro (P) Thr (T) Ala (A) UAU UAC UAAT UAG CAU CAC CAA CAG AAU AAC AAA AAG GAU GAC GAA GAG A Tyr (Y) STOP His (H) Gln (Q) Asn (N) Lys (K) Asp (D) Glu (E) G UGU UGC UGA STOP UGG Trp (W) Cys (C) CGU CGC CGA CGG AGU AGC AGA 1 AGG GGU- GGC GGA GGG Arg (R) Ser (S) Arg (R) Gly (G) U C A G U C A G U C A G U C A G Last base in codonarrow_forwardKnowing that the genetic code is almost universal, a scientist uses molecular biological methods to insert the human β-globin gene (Shown in Figure 17.11) into bacterial cells, hoping the cells will express it and synthesize functional β-globin protein. Instead, the protein produced is nonfunctional and is found to contain many fewer amino acids than does β-globin made by a eukaryotic cell. Explain why.arrow_forward
- Shown below is an R loop prepared for electron microscopy by annealing a purified eukaryotic messenger RNA with DNA from a genomic clone containing the full-length gene corresponding to the mRNA. (a) How many exons does the gene contain? How many introns? (b) Where in this structure would you expect to find a 5′,5′-internucleotide bond? Where would you expect to find a polyadenylic acid sequence?arrow_forwardConsider the following tRNAs, where the numbered forms represent the amino acids associated with them, answer briefly: PICTURE Question 1: The numbering indicates the order in which these tRNAs are recruited to the A site of the ribosome. Write the sequence of the mRNA being translated in the 5' - 3' direction Question 2: What is the amino acid sequence of the produced polypeptide? Question 3: Researchers discover that a mutation is in the anticodon of the gene encoding the proline tRNA of an individual. The anticodon sequence is normally 3' GGA 5', but in this individual the anticodon sequence is 3' GGG 5'. It appears that this individual suffers no adverse consequences. How can this be? (2 response items)arrow_forwardThe sequences of DNA bases below represent parts of the genes responsible for the production of one type of protein, an enzyme, produced by Botana curus and Species X, Y, and Z Under each DNA sequence, write the complementary messenger RNA base sequences that each of these gene fragments would produce. Note: Unlike during DNA replication, in the production of messenger RNA, the DNA base “A” specifies the RNA base “U.”. Use the universal genetic code table provided (see Universal Code attachment) to translate the messenger RNA base sequences into sequences of amino acids in the protein produced by each species. Write the sequences of amino acids under the messenger RNA sequences.arrow_forward
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